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Bureau of Mines Information Circular/1982 



Reduction of Airborne Contaminants 
From Welding Exhaust 
at Surface Mines 



1 



By G. K. Derby 



1 




UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 8868 

Reduction of Airborne Contaminants 
From Welding Exhaust 
at Surface Mines 

By G. K. Derby 




UNITED STATES DEPARTMENT OF THE INTERIOR 
James G. Watt, Secretary 

BUREAU OF MINES 
Robert C. Horton, Director 



6 







This publication has been cataloged as follows: 



Derby, George K 

Reduction of airborne contaminants from welding exhaust at 
surface mines. 

(Information circular ; 8868)' 
Includes bibliographical references, 
Supt. of Docs, no.: I 28.27:8868. 



1. Strip mining— Safety measures. 2. 
Fume control. 4. Dust control. I. Title. 



Welding— Safety measures. 3. 
II. Series: Information circu* 



lar (United States. Bureau of Mines) ; 8868. 



TN295.U4 622s [671. 5'2] 



81-607864 



AACR2 



CONTENTS 

Page 

\^<;^ Abstract 1 

^ Introduction 1 

^ Background study 2 

'V^ Contaminants and health hazards 2 

^ Problera areas In surface mines 4 

Problems outside the raining Industry 4 

Exhaust systems 5 

Testing procedures 9 

Test results 10 

Conclusions 11 

ILLUSTRATIONS 

1. Wlddervac welding-exhaust unit with 4-lnch nozzle 6 

2. Coppus Portaf liter with flexible tubing and nozzle removed 7 

3. Coppus Jectalr with flexible tubing removed 8 

4. Racal Airstream welding helmet , 8 

TABLES 

1, Possible particulate contaminants from welding fumes 3 

2 , Total particulate levels 10 

3 , Concentrations of contaminants 10 



V 



REDUCTION OF AIRBORNE CONTAMINANTS FROM WELDING 
EXHAUST AT SURFACE MINES 

by 

G. K. Derby 1 



ABSTRACT 

The Bureau of Mines studied the problems caused by airborne contaminants 
from welding exhaust in surface raining operations and investigated equipment 
designed to reduce existing hazards. Four commercially available welding-fume 
exhaust units were tested to determine their effectiveness. Results indicated 
that the four units had the capability of controlling airborne particulate 
concentrations and bringing them to within allowable exposure limits. 

INTRODUCTION 

Some mining and processing operations produce airborne contaminants at 
concentrations that are considered unsafe by the Mine Safety and Health Admin- 
istration (MSHA), U.S. Department of Labor. A recent Bureau of Mines report 
on inhalation contaminants^ stated that three sources of excessive air contam- 
ination were found in surface metal and nonmetal facilities: (1) welding 
fumes, (2) fumes from metal cutting, and (3) solvent vapors from degreasing 
operations. 

Welding personnel and others who are required to work near field repair 
operations have complained that the welding emissions are highly irritant and 
at times nausea-inducing. But coal mine operators and MSHA regional field 
office personnel have reported problems in complying with MSHA regulations 
because of the lack of availability of suitable, effective equipment to over- 
come problems encountered during field repairs. 

^Engineering technician, Spokane Research Center, Bureau of Mines, Spokane, 
Wash. 

^LFE Corp. Handbook for Surveys of Inhalation Contaminants in Above-Ground 
Metal and Nonmetal Mining and Processing Work Areas. Bumines Open File 
Rept, 9(l)-80, 1977, 87 pp.; available for consultation at Bureau of Mines 
facilities in Denver, Colo,, Twin Cities, Minn., Bruceton and Pittsburgh, 
Pa., and Spokane, Wash.; U.S. Department of Energy facilities in Carbon- 
dale, 111., and Morgantown, W. Va.; National Mine Health and Safety Acad- 
emy, Beckley, W. Va.; and National Library of Natural Resources, U.S. 
Department of the Interior, Washington, D.C.; and from National Technical 
Information Service, Springfield, Va., PB 80-143969. Contract JO255001. 



In response to these concerns, and as part of its program to develop 
safer work practices and reduce industrial hazards in surface mining, the 
Bureau of Mines established a research project with these objectives: (1) to 
identify welding fume problems and problem areas in surface mining, (2) to 
determine whether particulate-emission control devices were commercially 
available, and, if so, to test a selection of then to demonstrate their abil- 
ity to reduce hazards to acceptable threshold limit values, (3) to relay the 
information obtained to industry, and (4) to determine whether research was 
needed to develop emission control devices to fit the particular needs of the 
surface raining industry, A solution to the problem of welding exhaust would 
also apply to fumes from metal cutting, which are very similar. 

In the research reported here, the Bureau's Spokane Research Center 
assessed the health hazards caused by welding and metal cutting and investi- 
gated four devices that control the concentrations of particulates released to 
the air. 

BACKGROUND STUDY 

A background study was completed to assess the specific problems caused 
by welding emissions, the seriousness of these problems, and what means, if 
any, were available to eliminate them. 

Contaminants and Health Hazards 

Welding (and oxyacetylene metal cutting) may produce any one or a combi- 
nation of at least 20 different types of particulate contaminants that- can 
cause harmful effects and even death (table 1). The hazardous particulate 
substances not only endanger the persons performing the welding or cutting, 
but may also affect others in the vicinity of the sources of contamination. 



TABLE 1. - Possible particulate contaminants from welding fumes 



Particulate 



Aluminum oxide, 
Beryllium dust, 



Cadmium dust, 
Carbon black, 
Chromium 



Copper fumes, 
Fluorides. . . 



Iron oxide, 

Lead 

Manganese. , 
Mercury. . . , 



Molybdenum, 



Nickel metal. . , 
Nickel sulfide, 
Silicates: 

Iron 



Sodium , 

Tin oxide , 

Titanium dioxide.., 
Vanadium pentoxlde. 



Zinc oxide. . . , 

Asbestos: ^ 
Amoslte. . . . , 
Crocldollte, 
All other... 



Effect 



Alumlnosls 

Berylliosis; lesion of the skin, 
liver, kidneys, spleen, and lymph 
nodes. 

Pulmonary edema 

Anthracosls 

Bronchospasm, bronchitis, edema, 
hypersecretion, asthma. 

Nausea, vomiting, metal fume fever, 
ulceration of the cornea. 

Change In bone structure, respira- 
tory and other problems. 

Slderosls 

Cramps , nausea 

Total disablement 

Kidney damage, vomiting, diarrhea, 
gingivitis. 

Bronchial and alveolar Irritation, 
liver and kidney problems. 

Cancer 

do 

Pneumoconiosis, respiratory. 
Insufficiency. 

do 

Stannosls 

Fibrosis 

Conjunctivitis, pharyngitis, bron- 
chopneumonia, chronic bronchitis. 

Zinc chills 



Asbestosls, cancer, 

do , 

do , 



TLV-TwA, 
mg/m^ 



10 
.002 

.05 
3.5 
.5 

.2 

2.5 

5 

.15 
1.0 

.05 



1.0 
1.0 

10 

10 
2 
10 
.5 



.5 
.2 



^American Conference of Government Industrial Hyglenlsts. Threshold Limit 
Values for Chemical Substances In Workroom Air. ACGIH, Cincinnati, Ohio, 
1980, 93 pp. TLV-TWA (threshold limit values/tlme-welghted averages) are 
the concentration levels of airborne contaminants to which nearly all work- 
ers can be exposed for a normal 7- or 8-hour workday, or 40-hour workweek, 
without adverse effect. These values should be used as guides In the con- 
trol of health hazards, not as fine lines between safe and dangerous 
concentrations . 

^TVL-TWA for asbestos Is given In number of fibers greater than 5 ym In length 
per cubic centimeter of air. 

Source: Wldder Corp. Welding Bulletin WCN 11. 1977, A pp.; now Included In 

The Problems With Welding Fumes and How To Solve Them, by A. H. Krleg; 
Wldder Corp., Naugatuck, Conn., 1979, 30 pp. 



Airborne contamination problems may be increased further by other factors 
such as prior solvent degreasing or welding coated surfaces. Wet solvents may 
let off chlorinated vapors that can, in turn, be broken down by ultraviolet 
radiation in gas-shielded arc welding to produce phosgene gas, which is highly 
toxic. Surfaces coated with paint containing chrome, zinc, or lead under the 
high heat of welding will also produce toxic fumes. Dangerous reactions can 
also take place during the welding of plated surfaces that contain cadmium, 
chrome, or zinc. Filler metals, fluxes, lubricants, and pickling solutions 
may also produce injurious gases and particulates when subjected to welding 
heat. 

The possibilities for harm are enormous, and it is impossible to protect 
the worker from each of them individually. The only solution is proper protec- 
tion from the welding emissions themselves. Adequate ventilation or purifica- 
tion of the airborne exhaust is therefore a necessity. The particulate 
contaminants can be neutralized or vented to a location where the harmful 
effects they produce are minimized or eliminated. The highly toxic and haz- 
ardous gases also emitted during welding will be the subject of a future 
Bureau of Mines study. 

Problem Areas in Surface Mines 

An investigation was conducted to determine which areas of the surface 
facilities were experiencing the greatest difficulties. It was found that no 
great problems are experienced when welding tasks are performed within desig- 
nated maintenance work areas. Adequate exhaust systems are procurable, and 
most permanent maintenance facilities with fixed areas for performing welding 
tasks have proper equipment installed that is capable of overcoming welding 
emission problems. However, difficulties arise when welding tasks are per- 
formed outside established work areas, especially where work is done in the 
field within confined spaces, such as inside large equipment or inside drag- 
line and shovel buckets. 

Some mines have exhaust systems for work performed in the field. The 
units are generally assembled or fabricated from commercially available mate- 
rial and attached to the welding truck. Large-diameter flex tubing (up to 
12-in-diam) is commonly used for air evacuation from the point of welding to 
an eduction blower mounted on the welding truck. However, this tubing is 
unwieldly and difficult to maneuver in confined equipment interiors. Mainte- 
nance personnel are sometimes unwilling to use these exhaust units because of 
the difficulty in setting them up. The workers would prefer a small, compact 
unit, which could be handled by one or two people at or near the point of 
welding, eliminating the need for extensive ducting. Dilution and dispersion 
of fumes would be acceptable, but purification or filtration of the fumes to 
protect other personnel in the area would be preferable. 

Problems Outside the Mining Industry 

These problems are not confined to the mining industry. Safe evacuation 
of contaminant emissions when welding is performed in confined spaces away 
from established fabrication areas has been a recognized problem in many 



branches of industry here and in other countries. Research has been conducted 
and equipment developed to deal with the problem, especially in the English 
mining and Swedish shipbuilding industries. A very thorough study^ of the 
problem was completed in 1974, at the Uddevalla Shipyard in Sweden, The study 
detailed the difficulties the shipbuilders were having with contaminant emis- 
sions from welding and the development and testing of equipment to reduce or 
eliminate the problems. 

Exhaust Systems 

A market study uncovered numerous exhaust systems using various methods 
to evacuate or purify industrial contaminants. Small portable units accepta- 
ble for this project were readily available. Four units that used different 
methods of contaminant evacuation or treatment were tested: 

1. Widdervac** Model 821, Widdervac Corp., Naugatuck, Conn. (fig. 1). 
Welding emissions are drawn in through the nozzle and evacuated via a 2-in- 
diam flexible hose to the exhaust unit, which houses a spark arrester, replace- 
able filter, vacuum pump, and motor. The filtered air is exhausted into the 
atmosphere. The unit is powered by 115 volts ac. It is a derivative of the 
unit developed under the Uddevalla Shipyard study. 

2. Coppus Portafilter, Coppus Engineering Corp., Worcester, Mass. 

(fig. 2). Welding emissions are evacuated via a 4-in-diam flexible hose (noz- 
zle optional) to the exhaust unit, which houses a replaceable filter and a 
centrifugal-type blower-exhauster pump. Filtered air can be discharged at the 
unit or through a second flexible hose to clear the area. The unit tested was 
powered by a 115-volt ac, 1/2-hp motor. 

3. Coppus Jectair Model 3, Coppus Engineering Corp., Worcester, Mass. 
(fig. 3). Compressed air is admitted through a single side chamber leading to 
the nozzle chamber. The compressed air creates a venturi action, which 
induces a large volume of surrounding air to enter through the inlet. The air 
is then discharged through the horn-shaped diffuser, which can be coupled to a 
7-in-diam flexible hose that conveys the contaminated air to an area away from 
the point of welding. At this point, the welding emission should be diluted 
(by the injected compressed air and the neutral atmosphere sucked in with the 
welding fume) to a safe level. 

4. Racal Airstream welding helmet, Airstream, Rockville, Md. (fig. 4). 
This unit is designed for the protection of the individual worker. It con- 
sists of protective helmet and faceshield, air pump, replaceable filters, and 
battery pack. Air is drawn through a combination filtration-battery pack worn 
with a harness on the welder's back. The filtered air passes through 1-1/2-in- 
diam flex tubing to a rear inlet on the helmet. The helmet is fitted with an 
intergasketed faceshield that guides the filtered air over the breathing zone 
of the user. This unit has received MSHA certification. 

"5 — — ■ 

^Ahlstrand, H. , and P. Lidehall. Evaluation of Spot Evacuation System for 
Weld Smoke at Uddevalla Shipyard. Uddevalla, Sweden, April 1974, 56 pp. 

^Reference to specific equipment, trade names, or manufacturers does not imply 
endorsement by the Bureau of Mines, 





FIGURE 2. - Coppus Portafilter with flexible tubing and nozzle removed. Overall dimensions: 
20 by 17 by 40 inches; weight: 11 pounds. 




FIGURE 3. - Coppus Jectair with flexible tubing removed. Overall dimensions: 7 inches in 
diameter, 31-1/2 inches long; weight: 9 pounds. 




FIGURE 4. - Racal Airstream welding helmet. Weight of filter and helmet: 9 pounds. 



The number of units tested was controlled by the funding and time limits 
of the project. These particular units represent a range of equipment using 
different methods to overcome welding contaminant problems. The choice of 
these four units does not imply that they are the preferred or the only 
acceptable ones. Many other types are currently available, which have certain 
characteristics that will appeal to individual potential users. Final selec- 
tion of a unit will depend on the user's particular needs. 

TESTING PROCEDURES 

Welding emission samples were taken in a test cell made from commercially 
available welding screen. It measured 4 by 4 by 6 feet, with air circulation 
coming in from the bottom and exiting from the top. Transparent screening was 
used so that the welder was not visually isolated. Emissions were monitored 
and analyzed for five common types^ of welding rods used in surface mining 
maintenance operations. The range of rods selected produced a variety of con- 
taminant substances. 

Contaminant sampling was restricted to particulate matter. During test 
runs of the Widdervac and Coppus units, a self-contained personal sampling 
unit was used, with the air-intake cassette worn on the user's collar. For 
test runs of the Racal helmet, the air-intake cassette was positioned inside 
the faceplate in the airstream passing through the user's breathing zone. 

Test base samples were taken with the sampler cassette placed in the area 
of a welder's normal breathing zone,^ approximately 12 inches above and 
slightly off center in relation to the point of welding. For protection, the 
Racal helmet was worn so that filtered air would be provided to the welder, 
with minimun disruption of welding emission collection. Normal fixed exhaust 
equipment was used to clear contaminants from the outer work area. 

Individual test runs were for 2 hours, with an airflow rate of 1,8 1/min, 
using the air-intake cassette field monitor with a 0,8-um pore-size membrane 
filter. Five test runs (one for the sample case and one for each unit tested) 
were completed for each type of welding rod used. Sample analysis for partic- 
ulate levels and certain types of metal contaminant exposure was performed by 
an independent laboratory. 

Sample analysis was performed by Northwest Health Services of Richland, 
Wash. A total of 35 cassette filters was evaluated; content determinations 
were made to establish levels of total particulate, iron, and manganese for 
25 samples, and total particulate, titanium, nickel, and chromium levels for 
the remaining 10. The total particulate concentrations were determined gravi- 
metrically, and the metal content was determined using atomic absorption or 
flame -emission spectroscopy. Analysis results indicated that all four units 
tested had the capability of reducing the welder's hazard exposure to particu- 
lates to within acceptable concentration limits. 

^For one type, the rods of three manufacturers were used, making a total of 
seven different rods tested. 
The normal breathing zone is the volume of air within about a 36-inch radius 
of the worker's mouth. 



10 



TEST RESULTS 

Table 2 reflects the total particulate count for the sample cases and for 
each system, tested for comparison purposes with each type of welding rod. 
The TLV-TWA for total welding fume particulates, other than those individually 
classified (table 1) is 5 mg/m^ .^ All values listed in tables 2 and 3 as 
"less-than numbers" (<) indicate that the results are below the limit of 
detection for that particular analysis. Drastic reduction in total particu- 
late level is evident from the sample case runs to those in which welding 
emission controls were used. Because of the predominate use of the ASME-E7018 
rod for general welding and repair work, the rods of three manufacturers were 
tested. No appreciable difference in the particulate levels produced by the 
three rods was noted, so results were averaged for simplification, 

TABLE 2. - Total particulate levels, milligrams per 





cubic 


meter 


of air 






Welding rod used-'- 


E70182 


E6010 


E6011 


E6013 


E8018-B2 


Sample case. 


30.5 

1.44 

1.34 

2.74 

.27 


86.3 
1.78 
.33 
<.2 
.22 


67.3 
1.93 
1.06 
.88 
<.2 


21.3 

1.38 

.90 

.49 

.05 


39.0 


Widdervac 


1.15 


Coppus Portafilter 

Coppus Jectair. 


.56 
.33 


Racal Airstream 


<.2 



^Rod number is designation used by the American Society of 

Mechanical Engineers (ASME). 
^Rods from 3 manufacturers were tested and the results 

averaged. 



TABLE 3. - Concentrations of contaminants, milligrams per 



cubic meter of air 


Welding rod used^ 


Manganese 


Iron 




E70182 


E6010 


E6011 


E70182 


E6010 


E6011 


Sample case ....•••••••.• 


1.2 

.54 
.046 
.092 
<.005 


3.09 
.78 
.006 
.008 

<.005 


2.31 
.039 
.016 
.033 

<.005 


5.12 
.42 
.45 
.59 

<.023 


43.0 

.88 

.16 

.34 

<.006 


30.5 


Widdervac ............... 


.45 


Coppus Portafilter 

Coppus Jectair. 


.3 

.34 


Racal Airstream 


<.025 




Tlt< 


anium 


Ni 


ckel 


Chr 


omium 




E6013 


E8018-B2 


E6013 


E8018-B2 


E6013 


E8018-B2 


Sample case 


0.85 
.02 
.08 

<.02 
.02 


0.31 

<.2 

<.2 

<.2 

<.2 


<0.01 
<.01 
<.01 
<.01 
<.01 


0.02 
<.02 
<.02 
<.02 
<.02 


0.04 
<.01 
<.01 
<.01 
<.01 


<0.03 


Widdervac 


<.02 


Coppus Portafilter 

Coppus Jectair 


<.02 
<.02 


Racal Airstream 


<.02 



^Rod number is ASME designation. 

^Rods from 3 manufacturers were tested and 



the results averaged. 



^Work cited in footnote 1 of table 1. 



11 



Table 3 reflects filter analysis for detection and level of specific 
metals known to be emitted during combustion of certain welding rods. Confir- 
mation of unhealthy levels of contamination was not directly a part of this 
research, but these results clearly show that the manganese and iron levels in 
the sample cases were well above the threshold values given in table 1, at 
concentrations likely to cause serious health problems. Note that the reduc- 
tions from the sample case runs, in manganese and iron levels, are relatively 
proportional to the lowering of total particulate count for the different 
emission control systems. 

CONCLUSIONS 

Welding produces air contaminants that present health hazards if not 
effectively diffused or eliminated. This is particularly a problem when weld- 
ing is done in confined spaces and exhaust equipment is unavailable or unused. 

Although the surface mining industry has definite welding-fume problems, 
they are not peculiar to mining. Private Industry has developed technology to 
overcome the problem of controlling particulate emissions. Four small, porta- 
ble devices were tested and shown to reduce particulate concentrations to 
acceptable levels. (These devices were not graded or ranked, and many others 
are also commercially available.) 

It is recommended that a program be established to inform all segments of 
the mining industry of the equipment and methods currently available to con- 
trol welding-fume particulates. 

Because adequate equipment already exists, it is not recommended that 
the Bureau of Mines or other Government agencies proceed with development 
research in this area. Further research should be conducted to ascertain the 
hazards presented by gaseous welding emissions and the tools needed to mini- 
mize these hazards. 



irU.S. GOVERNMENT PRINTING OFFICE: 1981-505-002/130 int.-bu.of mines,pgh.,p a. 25821 



3349 










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